Gun turret for mobile tanks



W. M. POHL GUN TURRET FOR MOBILE TANKS Filed April 9, 1941 7 sheets-shea 1 Erl/life? poll@ Gttornegs Oct. 30, w45. wl. M. Pol-IL 2,388,919

GUN TURRET FOR MOBILE TANKS Filed April 9, 1941' '7 sheets-sheet 2 Y l I l J5' Y lwentor Gttornegs W. M. POHL GUN TURET FOR MOBILE TANKS Geit. 36, E5.

Filed Apr1`9, 1941 7 SheetsuSheet 3 IN VENT OR.

fer M POM @et 30, i5, A w. M.' Pol-n. 238,W

GUN TURRET FOR MOBILE TANKS Filed April 9, 1941 7 Sheets-Sheet 4 1NVENTOR, Waliez Pohl j my L H O P M. w

GUN TURRET vFOR MOBILE TANKS Filed April 9, 1941 '7 Sheets-Sheet 5 JNVENTOR. M Pohl v `Walfer IgM/m4 @et S, E945. W. M. PoHL GUN'TLIRRET FOR MOBILE TANKS 7 sheets-sheet 6 Filed April9, 1941 www ' mi@ ha @ci 36E, i945; W. M. PHL 2,3%,0

` GUN TURRET Foa MOBILE TANKS Filed April 9, 1941 '7- Sheets-Sheet 7 i HbrHeL.

aiented @ein 30, i945 GUN maar non Moenia 'ranks Walter M. liohl, New Haven, Conn., assigner to `Vickers, `Hnaorporated, Detroit, Mich., a corporation of Michigan lamination apr-i1 s, isn, sel-iai No. :istria` (ci. ssi-4i) malins.

This invention has to do with gun turrets for mobile tanks, and relates particularly to a system for the transmission of power in the manipula-I tion and control of turret mounted guns. It is especially adaptable to gun turrets in mobile tanks such as used by military land forces.

An important object of the presentinvention is the provision of an emcient hydraulic system which enables an operator to control the movement of 'guns and turrets with a minimum amount of physical effort. This promotes greater dexterity in the control of the guns and makes it possible for the operator to hold on the target at all times irrespective of the motion of tank or target and makes it possible to readily compensate for the rolling and pitching motion of the tank due to irregularity in the terrain over which it is moving. l

A further object is the provision of a servocontrol device which will cause the movement of gun, or gun and turret to be responsive to the movement of the sighting scope.

Other features have to do with the individual and combined operation of the various elements incorporated in the system which will be more clearly brought out in the specification and claims.

In the drawings:

Fig. 1 is an elevation, partly in section, showing the operating units and controls mounted within a tank body and turret, in accordance with the present invention.

Fig. 2 is a plan view of the structure shown in Fig. 1.

Fig. 3 is a schematic diagram with the various operating and control elements as shown in Figs. l and 2 arranged in working relationship and shown in cross-section for better illustration.

Fig. 4 is an elevation similar to Fig. 1, illustrating a modified arrangement wherein the control and operating units are so positioned as to permit the operator to be seated in a stationary position instead of moving with the turret as in Fig. 1.

Fig. 5 is a plan view illustrating the position and arrangement of the control and operating elements of Fig. 4.

Fig. 6 is a schematic diagram showing the operating and control elements of Fig. i in operative relationship, the said operating and control units being shown in cross-section.

Fig. 7 is a horizontal sectional view of a sta'- bilizing device which may be used in combination with the elevating control system as shown in Figs. 1 and 4 for automatically holding the gun on a targetwhile the tank is traveling over a rough terrain.

Figs. 8, 9 and 10 are enlargements, respectively, of the elevating and depressing motor, the training control, and the training motor shown in y Fig. 3.

Fig. 11 is an enlarged portion of Fig. 6.

Although the drawings show tanks of smaller sizes, it will be understood that the equipment is readily adaptable to larger models.

For a clear understanding of the present invention it should be understood that the system embodies a power supply, or an A-end unit I8 (see Figs. 1 and 3), for pumping oil under pressure. This includes a variable stroke pump driven by a gasoline engine (not shown) which also supplies tractive power through transmission I2 to the tank and which is therefore subject to speed iiuctuation. In order to compensate for these speedv uctuatlons and to maintain fluid output from the pump proportional to requirements, a flow control and pressurel responsive compensator is incorporated in the A-end I8, as best shown in Fig. 3, and as will presently be described. Fluid fromthe pump is conveyed through conduits to control valves where it is diverted to fluid motors for manipulating a gun I5 and turret i3 at the will of the operator.

The principal elements of the tank as shown in assembly in Figs. 1 and 2 are a tank body Ib, an engine drive shaft iI, a transmission gear case l2, a turret U3 movably mounted to rotate on the tank body about the vertical axis I4, and a gun or guns I5, movably mounted -for rotation about horizontal trunnion axis I6, for elevation and depression, which trunnion in turn is in a v iixed position with relation to the turret I3, so that gun and turret rotate together about v ertical axis I for traversing or training the gun. in azimuth.

The A-end, or pump and tank unit I8, forms the power element of a .hydraulic circuit, best shown in Fig. 3, and is mounted in a fixed position in the tank body I 0 where it is arranged to receive power from the engine through belt 26 or other suitable driving means. Pressure oil from the pump passes through a suitable conduit to a swivel joint assembly i9, which is arranged to rotate about axis It so as to provide' a means of conveying the duid to the various other components, which `are arranged to rotate with the turret I3. A hydraulic motor 20, or B-end, of standard type is carried by the turret I3 and provides a means for training the turret by transmitting torque through pinion 2l to ring gear 3i, which determines. the pump stroke.

l1 carried by the tank body. Speed and direction of rotation of the pinion 2| and the turret are controlled by manually operated valve 22.

Hydraulic force for elevating and depressing the gun is provided by hydraulic assembly 28, which is attached to' the turret at one end by pivot 21 and to the gun at its other end by pivot 28. Speed and direction of motion of the gun are controlled by means of a valve located within the cylinder assembly 2t and arranged for manual operation through signal means comprising linkage 2E connecting it to the sighting scope assembly 2M. f

The mechanics of operation will be better understood by referring to schematic diagram of Fig. 3. ln the A-end unit it, a variable delivery pump 29 o standard construction has a shaft 36, which isdriven continuously in the direction indicated by the arrow. Oil is delivered from the pump into a conduit 32 at a rate proportional to the angular displacement a of -a movable member The stroke is automatically controlled by means oi 'spring-loaded pressure responsive piston' 23,

which is designed to limit the power input by maintaining certain functional values between oil pressure and volumetric delivery. For exvalve will open to its normal position. This process will be repeated as often and as rapidly as necessary to maintainconstant maximum flow to the operating system.

It will appear obvious that the throttle valve 25, operating in combination with the compensator, is the essential element in controlling the rate of flow from the pump and that valve 38 is a secondary element which is incorporated to render the device more responsive to slight increases in the flow rate..

Swivel joint assembly |9 provides a means foxconducting the oil from the unit located in a fixed position in the tank body to the units located in the rotatable turret. It consists of a member 4U fixedlymounted on the tank body and to which the xed pipes are attached, and a movable member 4l to which the rotating pipes 43, 50 and 52 ample, as pressure tends to increase, the spring force against the piston 38 will be overcome in varying degrees, thus reducing the stroke in proportion to pressure. When the maximum pressure is reached for which the spring is designed, the stroke will be reduced to a point near zero, at which point the volumetric delivery will' Just equal theleakage in the system. This device not only protects the hydraulic system against excessive'pressure, but it also'prevents overloading of the engine by limiting the power input demand of the pump. As a further protection tothe hydraulic. system, an emergency relief valve 34 is incorporated in the pressure line. This relief valve is designed to open and dump the entire ilow of the pump into the supply tank in case the compensator fails to function when the maxi- `mum pressure is reached.

f The maximum flow from the pump is limited yto a predetermined rate by throttle valve 35 andy hydrostatic valve 3B, through which the oil must flow in passing from conduit 32 to conduit 21. The hydrostatic valve 3B is constructed with a piston portion 38 with equal pressure areas von both sides. It is normally held open by the light Spring 39 when the hydraulic pressure on both sides of the piston are equal, but will close and block or restrict the flow of oil to conduit 31 when a slight pressure differential exists on the upper side of the piston. Throttle valve 36 is designed to produce such pressure diilerential when the speed of the engine reaches a point where -the delivery ofthe pump exceeds the predetermined value. This automatic function is accomplished by adjusting the throttling valve to a position where it will permit free ilow for the normal requirements of the hydraulic motors 20 and '23, but when this rate of flow is exceeded, the resulting pressure dropacross the throttle will cause valve $8, to close and restrict the flow of oil. into conduit 31. 1

The closing of valve 38 will result in a pressure rise in conduit 32 which will react through the compensator to reduce the pump delivery by shortening the pump stroke. After the pump stroke has shortened sufllciently to compensate for theincreasedengine speed, the pressure differential on valve 36 will be neutralized andthe 75 are attached.

Fluid pressure in conduit 31 is conducted to an elevation control valve 44 and a training control will be made available to the hydraulic motor 20 or cylinder 22 upon opening :one of the control valves 48 or 44.

the training movement is desired. To train right.

valve 48 ismovedto the right where it admits pressure through conduit 41 to hydraulic motor 20 where it is converted into torque to rotate pinion 2| on ring gear i1, thus training the turret to the right. i t

The exhaust fluid from the hydraulic motor passes through conduit 48 to valve 46 where it is metered through tapered grooves 52 (Fig. 9), which provide a means of controlling the training speed in proportion to the displacement of valve 4,6. Exhaust flow from valve 22 is then returned to the supply tank through conduits 49, 50. and 5I. Training to the left is accomplished by shifting the control valve 40 to the left to reverse the direction of now to hydraulic motor 2l.

Conduit I! provides a means of returning excess oil from gear case Il to the supply tank through swivel Joint I8 and conduit I4. It will be noted that conduit l5 projects upward into the gear case to serve as a stand pipe, so as to maintain a constant@ oil supply in the case for lubricating the gearing.

Clutch II provides a driving connection between hydraulic motor unit 2l and training pinion 2|. In case of power failure the turret may be trained manually by attaching a crank to shaft lla. In this event the clutch may be temporarily disenlged so as to eliminate the resistance of the liquid in the hydraulic system during training movement. "I'he clutch is shifted by means of 'hond lever It.

The movements of the gun. in elevation and depression, are entirely responsive tothe movement lof sighting scope l., which, as best shown in Fig. 8, is manipulated by pistol grip l1. Scope Il is mounted on a horizontal pivot Ila which in turn is mounted on a vertical pivot llc. This motion is transmitted through V the control plunger Il and interconnec l linkage or si: il

means 2l between the sight l scope and spi g asesora It controlled valve de, which controls the ow of oil into cylinder 23.

In operation, to elevate the muzzle of the gun the pistol grip is manipulated so as to move the fore end of the sight upward. This causes valve et to be shifted upward where it admits pressure to the lower end of dpressure chamber 59 of the cylinder and vents chamber 6B to tank through conduits El! and i. The arrows along linkage 25 illustrate the movement for muzzle elevation. The gun will then move in elevation solong as the sight continues to move-in that direction. When the sighting scope comes to rest on the target, valve lid will also come to rest andI the follow up movement of the gun will cause the ports in cylinder 2S to overtake the valve and block the passage of oil to or from chambers 5s n In case of power failure, the gun may be controlled manually by grasping the stock. Under this condition the bypass valve-M may be temp orarily shifted to the manual position where it bypasses the oil in chambers E@ and et to eliminate hydraulic resistance to the ro'fement of the gun during elevationY and depression.

Inthe modification shown in Figs. 4, 5 and 6, the elements and their functional relations with each other are similar to those described above, and similar numbers refer to similar parts on the two schematic diagrams. The principal dierence between the operating and control elements in Figs. 4, 5 and 6, and the one previously described, with particular reference to Figs. 1 and 3, is in the arrangement of the various units. In

`the arrangement shown in Figs the operator sits at a fixed control station in the main body of the tank, from. which point he controls the movement of the gun and turret. It will also be noted that the hydraulic motor assembly 2% for training the turret lh is likewise mounted in a /xed position on the main body lb ofthe tank'and that the training ring gear i 'Eb is iixed as a part of the turret. This method of mounting the hydraulic motor b is desirable in the present arrangement in order to simplify the piping system and control mechanism.

The elevation and depression mechanism is the same as previously described in connection with Figs. l and 3, with the exception of the control linkage 25h, which, as best shown in Iiig. 6, is designed to permit linear motion to be` transmitted from the xed control station and handle 2gb through the swivel joint isb to control valve The essential diierence in the training mechanisms between Figs. l and 4 is the incorporation oi a follow-'up and response device in the modiilcation shown in Fig. 4.' The training motion is controlled by valve t5, which is designed for linear movement in a valve body 22a, but it is normally held in theneutral position, as shown by the cen'tering spring tt. In this-'position it blocks the pump pressure line t7 and hydrauli-l cally locks the turret in position by blocking both conduits 69 and lli of the hydraulic motor.

Linear motion is transmitted to valve t5 by rotating the helix 'li in the response gear lf2.

. is for connection to the ring circuit, not shown.

This iotary motion is transmitted from the'sighting scope assembly through gears 13, ld. l5, it

and slip joint l1.' The slip joint is designed/to transmit rotary motion to the helix without restricting the linear movement. Response motion is transmitted from the turret ring-gear l'ibv to gear 'l2 through gears 18, le, 8d, shaft 8i, gear 82.

In operation, movement of sight 58h and gear 'i3 results in movement of the valve 65 which is shifted in a linear direction td open and admit -pressure to the hydraulic motor 2th, through one or the other of conduits 6% or ld, depending upon the direction of motion desired. The response motion of the turret and shaft 8i then tends to reverse the valve and shut od pressure. In this manner training motion of the turret and sighting scope are synchronized and are equal in speed,

amplitude, and direction of rotation. This principle will be more readily understood by studying the operation for training in one direction.

VLet itfbe assumed that the turret is to be trained to the right, that is, in a clockwise direction as viewed in Fig. 5. Moving the pistol grip 51h to `the right rotates helix 'il in the direction which causes valve to move forward where it admits pressure to hydraulic motor 20h through conduit te. This pressure is converted into torque at the hydraulic motor 20h, thus causing the turret isb to rotate in the clockwise or train right direction. `Exhaust ow from the hydraulic motor 20h returns lto the control valve through conduit l@ and from there it is diverted to the supply tank through conduits @t and Elib. As the training movement continues, the response mechanism of the turret and shaft ti and connecting gears will tend to drive or rotate gear l2 on the helix and return valve 65 rangement shown in Figs. 4, 5 and 6 provides a means for synchronizing the gun with the sighting scope *in both training and elevating, and for controlling the same by means of a single control lever orpistol grip 51h. f The operating principles in training left are similar to those just described for training right. Fig. '7 is a fragmentary plan of a stabilizing device which is designed to be incorporated in the control mechanism of the elevating system for the gun in such manner as to compensate for any pitching motion of the tank which may ,be caused by irregularities in the terrain over which the tank is passing. The drawings represent the top plan of the device as it may be installed as a part of the control mechanism shown in Fig. 2. Pistol grip tlc is indirectly connected tothe sighting scope control plunger 83, of the is at 35h while the inertia wheel 85o, lies in ahorizontal plane. Any movement of the tank 2 and 3, and with the third element of the diderential restrained from rotation by the inertia dei vice, it will be readilyunderstood thatany movefment of the pistol grip 51h' will be transmitted through the differential gearing to plunger 83 and to the control valve link 25, for bringing the gun on the target. It will also be understood that any deviation of the tank from the plane 'which it was in at the time the gun was pointed will tend to move the gun off the target. The alignment of the inertia device', however, will not change from its' original plane and under such conditions it has thev eiect of introducing a correction factor proportional to the misalignmeent of the tank, so 'that the gun and sight will be held on the target, irrespective of the pitching motion of the tank. l Y

It will bev understood that the stabilizing device as illustrated in Fig. 7 may be added to the control unit of the ymodiiication illustrated in Figs. 4 and 6. In this case the actuation of thecontrol lever 25h and the control gear 'i3v 14 would be by means of a pistol grip through diierential gearing.

An important feature of the designs as shown in Figs. 3 and 6 is the arrangement of the conaasaom telescope 58b are stationary as far as trainingA movement is concerned, valve 65 would be closed and the trapped liquid would prevent or subdue kick back or overhaul such as would be caused by the iiring of a single gun which would tend to cause whip of the gun about the vertical axis of the turret. If the gun I5b should be ilred while the turret is training to the right, there would be a tendency for the turret and the gun to whip to the rightiand this motion transmitted through the shaft 8| and gears l2, I2 would move the valve @5 towards closed position to immediately set-up reaction against further whipping or overhaul movement of the turret. On the other hand, if the gun 24 should be fired during this right hand training movement, the first instantaneous reaction would be to cause further l, opening of the valve 65, thus directly 'countertrol valves and synchronized operating levers to produce an effective anti-kick against the recoil o'f the gun or guns. As best vshown in Fig. 3, the controllinkage 25 andthe ports connecting the control valve 44` with the chambers 59 and 60 are so arranged. that when the pistol grip 51 is moved upwardly for elevation, -valve 44 is likewise moved upwardly' to direct iluid pressure to the chamber 59.. If the gun is fired when the telescope 58 is on the target, the valve 44 will be in neutral, the ports will be closed andv any recoil will be absorbed by the oil in the cylinders; however, if the gun is iired as the same is being elevated, or for any reason the gun is moving counter-clockwise about the trunnions I6 at the time of firing, the counter-clockwise movement of the valve casing 23 willtend to move the valve 44 downwardly to close the valve, or move it to a point to admit liquid to the chamber 60, th'us in either case tending to counteract,

recoil 'of the gun. If the gun should .be tired while the pistol grip is moving downwardly,

which would be depression movement of the' would tend to keep the valve open so that oil i under pressure would continue to ilow' to the chamber 60, thus counteracting' the recoil action.

The anti-kick action oi.' the elevating-depression actuating and control membersI as shown in Fig. 6 is essentially the same'as thatl above described with specic reference to Fig'. 3. In addition, the control valve 22h, its associated Darts.

and the response mechanism for controlling the training movement, are so arranged and correlated that effective anti-kick action is obtained against the firing of only one of the 'gunsas shown in Fig. 5. If the pistol grip 57h and the acting the tendency of the gun and the' turret to whip tothe left. As will be readily seen in Fig. 6, the valve 65 and the response mechanism connecting the same to the turret are so designed and arranged as to prevent or subdue kick back or overhaul due to firing of one or the other of the guns during training movement to the left, in the same manner as above described with respect to training to the right.

What I claim is:

- 1. In an army tank, a stationary portion,l a movable gun supporting portion, a source of liquid under pressure in said stationary portion, motors in said movable portion for shifting the same and elevating a gun mounted thereon, conduits connecting said motors with said pressure source, means in said conduits for permitting y movement of said movable portion relative tosaid stationary portion comprising a central stud formation mounted on said stationaryfportion having conduits extending upwardly therein connecting with ports in the outer surface thereof, a portion mounted on said movable portion surrounding said stud having ports therein adapted to register with the ports in the surface of said stud, and conduits connecting the ports in said surrounding portion with the conduits of said movable portionl an operating scope on the stationary portion of the tank, follow valve means on said turret for controlling the elevating motor and linkage connecting the scope and the follow valve for operation of the valve, a portion of said linkage passing centrally through said stud and having longitudinal movement therein and serving as signalfand response mechanism.

2. In army tank, a revolving gun turret, a trulmion mounted gun on said turret, means `for eilecting the movement of said turret relative to said tank, a sighting scope on said turret mounted independentlyof said gun, a. source of hydraulic pressure, v a motor for-elevation adjustment of said'gun comprising a piston and rmi suspended from said turret, a cylinder on said gun to the rear of the trunnion thereof in which said piston is located, a valve block also movable with said gun connecting said pressure sourceI with said valve block, means connecting said valve block' with the respective ends ,of said cylassaoro portional to the movement of said scope in a follow-up arrangement.

3. In an army tank, a movable gun turret mounted thereon, hydraulic motor means for sluiting said turret, a gun movably mounted on ment of said scope lwill eiect simultaneous elevation of said gun, and a response mechanism operably connecting said gun and said control means whereby movement of said gun is directly proportional to the movement of said scope, and stabilizer means comprising a differential interposed in said signal means and a gyroscopic element connected to one element of said differential whereby change of level of said tank will impart correcting signals to said control means to maintain the aim of said gun.

4. In an army tank, a rotatable gun turret and a combined hydraulic and manually operated gun mounted on said turret, piston and cylinder structure connecting the turret and a portion of the gun for hydraulicallysupporting and controlling the movement thereof, and a follow up type control valve for controlling the flow of operating liquid to said piston and cylinder structure, and by-pass means to connect the ends ofY the cylinder to allow interow of said operating liquid thus permitting manual operation of the gun.

5. In an army tank, a rotatable gun turret` and a combined hydraulic and manually operated gun mounted on said turret, piston and cylinder structure connecting the turret and a portion of the gun for hydraulically supporting and controlling the movement thereof, a follow up type control valve connected to and movable with said cylinder for controlling the flow of operating liquid to said piston and cylinder structure, means to permit manual operation of the gum compris- 'ing by-pass conduits for operating liquid in said cylinder, andcentering means for said follow up valve for positively insuring centering of the valve parts when the gun is stationary.

6. In an army tank of the type having a rotatable gun turret and a gun carried thereby, hydraulic motors for training the turret and gun and for elevating and depressing the gun, at least one oi said motors being movable with said turret, a follow-up control valve integrally connected to and movable with said mst named'motor, a sighting scope, directional means directly connecting said scope and said valve for obtaining synchronous movement of the scope and gun, a source of pressure supply mounted in a iixed part of the tank. and distributing means for conducting uid under pressure from said pressure source to one or more .of said movably Y mounted motors.

'7. In an army tank, a rotatable gun turret, a source of hydraulic pressure, a hydraulic motor carried by the turret and hydraulically supporting one or more guns for elevating and depressing the same, and a manually controlled valve of the follow up type integrally connected to and movable with said motor for controlling the' dow of operating liquid to and from said motor and for directing said gun, said valve and said motor being so arranged as to prevent or subdue kick back due to ring of the gun or guns whether the gun is red when stationary or during elevation of depression thereof.

8; In an army tank, a rotatable gun turret, a hydraulic circuit including a source of pressure supply and a hydraulic motor for controlling training' of the turret and the gun or guns therein, and a confined hydraulic motor and control valve pivotally mounted on said turret and operatively connected to said gun or guns for elevating and depressing the gun or'guns, a sighting scope, gun directing means directly connecting said scope and elevating motor and control valve and indirectly connecting said scope and training motor through a follow up type valve for controlling movement of the gun and whereby movement of the gun and scope are synchronous and controlled by said single directing means.

9. In an army tank, a rotatable gun turret, a hydraulic circuit including asource of pressure supply and a hydraulic motor for controlling training of the turret andthe gun or guns therein, and a combined hydraulic motor and followup valve operatively connected to said turret and said gun or guns for elevating and depressing the gun or guns, a sighting scope, a single gun directing means directly connecting said scope and said combined motor and valve and indirectly connecting said scope and training motor through a followup type valve for controlling movement of the gun and whereby movement of the gun and scope are synchronous and controlled by said single directing means, the connecting means between said directing means and follow up valves being such that training and elevating movements are controlled entirely by movement of said single directing means by the operator. said follow up valves including response means for centering the valve member to the respective follow up valves when either or both of said movable members catches up with movement of said directing means, said follow up valves, connecting means and response means being so arranged as to prevent kick back ci the gun and prevent kick back or overhaul of the turret due to the ring of a wing gun in a multiple gun installation.

l0. In a land tank, a rotatable gun turret and a combined hydraulic and manually operated gun mounted on said turret, piston and cylinder structure connecting the turret and a portion of the gun for hydraulically supporting and controlling the movement thereof, a follow-up type control valve for controlling the iow or operating liquid to said piston and cylinder structure, means for manual manipulation as a control lever, and linkage connecting said means and said valve serving as a signal means to said valve4 and also as a response mechanism to reflect movement of said gun and limit -movement thereoi to a proportional amount of the movement of the manual means.

1l. In a land tank, a rotatable gun turret and a combined hydraulic and manually operated gun mounted on said turret, hydraulic motor means for elevating the gun or rotating the turret, a source of liquid under pressure ycompris-4 liquid from the source of pressure to the motors, a means for manual manipulation as a control lever, and linkage connecting said means and said valve serving as a signal means to said valve and also as a response mechanism to reflect movement of said gun and limit movement thereof to movement of the manual means.

12. In an army tank of the type having a rotatable covering gun turret for carrying an operawr and 'a gun supported therein, a hydraulic motor pivotally suspended on the turret above the operators position and operatively connected ,to the gun for elevating and depressing the gun,

, and said linkage signal means to correct for para follow-up control valve connected to and movable with said gun. a sighting scope, and directional means directly connecting said scope and said valve for obtaining synchronous movement Aoi the scope and gun.

13. In an army tank of the type having a rotatable covering gun turret and a gun supported therein, a hydraulic motor having one of two relatively movable elements pivotally suspended on the turret and the other operatively connected to the gun for elevating and depressing the gun, a follow-up control valve integrally connected to and `movable with the element of said motor' which is connected to the gun, a sighting scope, and directional means directly connecting said scope and said valve for obtaining synchronous movement of the scope and gun.

14. In a land tank, a rotatable gun turret and a combined hydraulic and manually operated gunv mounted on said turret, piston and cylinder structure connecting the turret and a portion of the gun i'or hydraulically supporting and controlling the movement thereof, a follow-up type control allax dinerences between said sighting scope and said gun.

15. In an army tank, a rotatable gun turret, a hydraulic circuit\including a source of pressure supply and a hydraulic motor for controlling training of the turret and the gun or guns therein, and a combined hydraulic motor and control valve pivotally mounted on said turret and operatively connected to said gun or guns for elevating and depressing the gun or guns, a sighting scope, gun directing means directly connecting said scope and elevating motor and control valve and indirectly connecting said scope and training motor through a follow up type vrlve.

for controlling movement of the gun and whereby movement of the gun and scope are synchronous and controlled by said single directing means, and means to adjust the relationship between said scope vand said followup valve to correct for parallax diierences between said scope and said f gull OI guns.

WALTER M. POHL. 

